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Bowel Wall Visualization Using MR Enterography in Relationship to Bowel Lumen Contents and Patient Demographics
Ting Ting Zhang1,2, Wei-Chou Chang1,3, Zhen Jane Wang1
1Department of Radiology and Biomedical Imaging, UCSF Medical Center, San Francisco, California, USA.
Background:
MR enterography (MRE) is generally performed without bowel preparation, but the frequency and extent by which bowel contents affect bowel wall visualization are poorly described in the literature.
Purpose:
To evaluate MRE bowel wall visualization quality relative to bowel lumen contents and patient demographics.
Study Type:
Retrospective, single-center.
Population:
One hundred and four consecutive patients (mean age 29 years, range 5-76 years) without prior bowel resection who had undergone MRE.
Field Strength/Sequence:
3 T (N = 87) or 1.5 T (N = 17)/T2-weighted single-shot spin echo (T2WI) and fat-saturated T1-weighted gradient echo (T1WI) without and with gadolinium.
Assessment:
For the proximal and distal jejunum and ileum and colon, three readers independently categorized bowel lumen signal (water = bright T2 dark T1, T1-bright, or air = dark T2 and T1 signal) and scored distension (0 = poor, 1 = moderate, 2 = well) and wall enhancement (0 = unclear, 1 = perceptible, 2 = clear) based upon gadolinium enhanced T1WI for the 104 MRE exams). The bowel visualization score was the sum of the wall enhancement and distension scores and was considered adequate if ≥3.
Statistical Tests:
Wilcoxon signed-rank test.
Results:
The bowel lumen content was water signal in 93% (97/104 scans), 92% (95/104), 98% (102/104), and 93% (92/104) of the proximal and distal jejunum and proximal and distal ileum, respectively, but only in 12.5% (13/104) of the colon. There was adequate bowel visualization of 53.8%, 77.8%, 84.6%, 90.4% of the proximal and distal jejunum and proximal and distal ileum, respectively, but only 19.2% of the colon. In children (age < 18 years), the visualization score of the ileum was lower when the adjacent colon contained air (2.4 ± 0.97) compared to water (3.75 ± 0.29, P < 0.05) or T1-bright material (3.21 ± 0.82, P < 0.05).
Data Conclusion:
Without bowel preparation, colon wall visualization was often unsatisfactory at MRE, and air-filled colon also degraded small bowel visualization, particularly in children.
Level Of Evidence:
4 TECHNICAL EFFICACY: Stage 1.
Insights
MR enterography (MRE) bowel visualization is often poor in the colon without preparation. Air in the colon can also negatively impact small bowel visualization, especially in pediatric patients.
Area of Science:
- Radiology
- Gastroenterology
- Medical Imaging
Background:
- MR enterography (MRE) is a key imaging technique for evaluating the small bowel.
- Standard MRE protocols typically do not include bowel preparation.
- The impact of bowel contents on MRE visualization quality is not well-documented.
Purpose of the Study:
- To assess the relationship between bowel lumen contents and MRE bowel wall visualization quality.
- To investigate the influence of patient demographics on MRE visualization.
Main Methods:
- Retrospective analysis of 104 MRE exams performed at a single center.
- Assessment of bowel lumen signal (water, T1-bright, air) and distension/enhancement scores.
- Evaluation of visualization quality using T2-weighted and fat-saturated T1-weighted sequences with gadolinium contrast.
Main Results:
- Water was the predominant content in the small bowel (92-98%), but rare in the colon (12.5%).
- Adequate visualization was achieved in 54-90% of the small bowel segments but only 19% of the colon.
- In children, air in the colon significantly reduced ileal visualization compared to water or T1-bright content.
Conclusions:
- MRE without bowel preparation frequently results in unsatisfactory colon visualization.
- Air-filled colon segments can impair small bowel visualization, particularly in pediatric MRE studies.
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